Currency conversion fails with empty GBP rate causing zero amount conversions

[osw282]

Issue Description

The currencyservice is experiencing critical conversion errors that result in zero amounts when converting from/to certain currencies. The logs show multiple instances of:

Currency conversion resulted in zero amount, switching back to original currency

Root Cause Analysis

After examining the source code in src/currencyservice/server.js and the currency data in src/currencyservice/data/currency_conversion.json, I've identified the root cause:

The GBP (British Pound) conversion rate is an empty string ("") instead of a numeric value.

In the currency_conversion.json file:

"GBP": "",

When the conversion function attempts to divide by an empty string, JavaScript coerces it to 0, which causes the mathematical operations to result in zero amounts:

const euros = _carry({
  units: from.units / data[from.currency_code],  // Division by empty string = 0
  nanos: from.nanos / data[from.currency_code]   // Division by empty string = 0
});

Impact

• Currency conversions involving GBP fail and fallback to original currency
• User experience is degraded when attempting GBP conversions
• Error logs are generated repeatedly, potentially causing alert fatigue
• The service attempts to send Slack notifications (with cooldown) for each failed conversion

Recommended Fix

Update the currency_conversion.json file to include a valid numeric conversion rate for GBP. Based on typical EUR to GBP rates, a value around 0.85 to 0.90 would be appropriate:

"GBP": "0.8631",

Additionally, consider implementing input validation in the conversion function to:

1. Check for empty or invalid conversion rates before performing calculations
2. Log warnings about invalid conversion data
3. Gracefully handle missing or invalid currency rates

Files to Modify

• src/currencyservice/data/currency_conversion.json - Fix the empty GBP rate
• src/currencyservice/server.js - (Optional) Add input validation for conversion rates